import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.Socket;

public class UdpServer{
    private DatagramSocket socket=null;
    public UdpServer(int port) throws IOException {
        socket=new DatagramSocket(9090);
    }
    public void start() throws IOException{
        System.out.println("服务器启动");
        while (true){
            DatagramPacket requestPacket=new DatagramPacket(new byte[4096],4096);
            socket.receive(requestPacket);
            String request=new String(requestPacket.getData(),0, requestPacket.getLength());
            String response= process(request);
            DatagramPacket responsePacket=new DatagramPacket(response.getBytes(),response.getBytes().length,
                    requestPacket.getSocketAddress());
            socket.send(responsePacket);
            System.out.printf("[%s/%d] request=%s ,response=%s\n",requestPacket.getAddress(),requestPacket.getPort(),
                               request,response);
        }
    }
    public String process(String response){
        return response;
    }

    public static void main(String[] args) throws IOException {
        UdpServer server=new UdpServer(9090);
        server.start();
    }
}
